Ram construction for lift truck



Jam. 28, 1%8 B. a. uuNsKl RAM CONSTRUCTION FOR LIFT TRUCK 4 SheetsSheet1 Filed Dec. 30, 1954 INVENTOR. 6 Z do/xhw/ flw rmu u W MFW m /DATTORA/f) Jan 25%, 195% s. 1. ULINSK! RAM CONSTRUCTION FOR LIFT TRUCK 4Sheets-Sheet 2 Filed Dec. 50, 1954 INVENTOR. I1 I A TTORNfY B. l. uLlNKl RAM CONSTRUCTION FOR LIFT TRUCK g un. 8 2

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4 Sheets-Sheet 5 Filed Dec. 30, 1954 INVENTOR. I /MZ/ r C/ ATTORNEY 5.l. ULINSKI RAM CONSTRUCTION FOR LI IIFT TRUCK 4 Sheets$heet 4 Filed Dec.30, 1954 AMEN 3 v I ll \\l /M/& WY m w w 7 wmww m M 1. 1 1 w. A w 5 2 1Ai a] a SH yd T @H M i 42 N United States Patent RAM CONSTRUCTION FORLIFT TRUCK Bronislaus I. Ulinski, Chicago, 11]., assignor to The Yale &Towne Manufacturing Company, Stamford, Conn., a corporation ofConnecticut Application December 30, 1954, Serial No. 478,807

3 Claims. (Cl. 187-9) This invention relates to a truck of the classdisclosed in my earlier patent, No. 2,554,930, for a Lift Truck. In thatpatent I disclose a truck having primary uprights, secondary uprightsmovable vertically on the primary uprights, and a load carriage movableon the secondary uprights. A pair of sequentially operated rams areutilized with one ram functioning between the carriage and the secondaryuprights for lifting the carriage relatively to the secondary uprights,the other ram functioning between the secondary uprights and the primaryuprights for lifting the secondary uprights together with the carriageafter the carriage has been fully elevated on the secondary uprights.

The contribution of my earlier patent is a very considerable one and hasbeen recognized by the truck industry as one of great value. Theinvention of this application comprises a contribution over that of myearlier patent in that through my newest invention I eliminate the useof movable hose required for the movement of the hydraulic fluid to thesequentially operated rams of my patented structure. In addition, Ieliminate the need for outside piping between the rams, requiring onlythat fluid be moved from the source of fluid pressure into a stationarypart of one ram. I accomplish these things while utilizing extremelysimple ram structure, with separate cylinder and piston elements foreach ram, rather than the telescoping ram arrangements utilized byothers in order to contribute this feature.

In brief, I utilize a ram functioning between the primary uprights andthe secondary uprights, and a pair of additional rams functioningbetween the secondary uprights and the lifting carriage, with therelatively stationary element of each of the pair of rams being fixed tothe relatively movable element of the first ram. While I prefer to use apair of rams operating between the carriage and the secondary uprights,those skilled in the art will appreciate that this may not be necessaryin many assemblies and that a single ram may be utilized.

As a further feature of the invention, the ports traversed by the fluidbetween the rams are formed in the securing means holding the ramelements together, so that no outside piping is required. It will beappreciated that the ports need not actually be formed in the securingmeans since conceivably the rams could be secured at one point, withfluid carrying pipes positioned between the rams at another point.Therefore, this portion of my invention should be construed ascontributing the feature of fluid carrying means between the rams sopositioned and related that the said fluid carrying means have nomovement relatively to the parts of the rams that are secured to oneanother.

I have thus outlined rather broadly the more important features of myinvention in order that the detailed description thereof that followsmay be better understood, and in order that my contribution to the artmay be better appreciated. There are, of course, additional features ofmy invention that will be described hereinafter and which will form thesubject of the claims appended ICC hereto. Those skilled in the art willappreciate that the conception on which my disclosure is based mayreadily be utilized as a basis for the designing of other structures forcarrying out the several purposes of my invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions as do not depart from the spirit and scope of myinvention, in order to prevent the appropriation of my invention bythose skilled in the art.

Referring now to the drawings:

Fig. 1 shows an industrial lift truck utilizing my novel sequential ramstructure.

Fig. 2 shows a front view of my invention.

Fig. 3 is a sectional side view on the line 3-3 of Fig. 2.

Fig. 4 is a longitudinal section showing the construction of the rams.

Fig. 5 is a view taken on the line 5-5 of Fig. 4.

Fig. 6 shows a top plan view of the invention.

Fig. 7 is a cross section on the line 77 of Fig. 2.

Fig. 8 and Fig. 9 show schematically the operation of the rams.

In order that my invention may be readily understood,

.1 show in Fig. 1 a lift truck having a pair of primary uprights 10, apair of secondary uprights 11 that move vertically on the uprights 10,and a load carriage 12 moving vertically on the secondary uprights 11.It will be well to state, before describing my ram construction indetail, that the particular movements of the carriage and uprights arelike those described in my patent, No. 2,554,930, to which I havealready referred, with the load carriage 12 lifted first to the upperend of the secondary uprights 11, and the carriage 12 and secondaryuprights 11 then lifted together relatively to the primary uprights 10.The actual upright structure that I prefer to utilize is quite similarto that shown in my earlier application Serial No. 346,603, filed April3, 1953, now Patent No. 2,788,863, having the primary and secondaryuprights 10, 11 aligned relatively to one another in a directiontransverse to the longitudinal axis of the truck.

This construction will be best understood from Fig. 7, in which I showthe secondary uprights 11 mounted intermediate the primary uprights 10through rollers 13 that are engaged in channels in the primary uprights.The load carriage 12 is mounted through a pair of brackets 14 at itsrear side, these brackets 14 having rollers 15 engaged in the channelsof the secondary uprights 11. The carriage 12 preferably is equippedalso with guide rollers 16 that engage the sides of the secondaryuprights 11 to hold the carriage against transverse movement. Theparticular arrangement has certain advantages that are well described inmy earlier application, but it should be understood that the detailsthrough which the carriage and uprights are mounted are not important toan understanding of my present invention. It is important here to knowprincipally that the carriage is mounted to move vertically on thesecondary uprights, with these uprights mounted to move vertically onthe primary uprights.

In describing the extremely novel sequential ram structure that Icontribute by my invention, it will be best to consider first the ram 17that I utilize for lifting the secondary uprights 11. I shall referlater to the ram 17 as the second ram, however, because other rams thatI shall describe act first to lift the load carriage. The ram 17 in thepreferred form of my novel structure has a relatively long piston 18that is mounted at its lower end upon the primary uprights 10 of thetruck, as may be seen in Figs. 1 and 3. I show for the particularpurpose a bearing plate 19 that is seated upon a bottom cross member 20on the primary uprights 10, with a reduced end portion 21 on piston 18engaged in an opening in the plate 19 and cross member 20 and held by asnap ring 22. I prefer to reinforce the plate 19 and cross member 20through-a pair of vertical plates 23, Figs. 1 and 7, that are attachedto an intermediate cross member 24 at the rear side of the primaryuprights 10.

A relatively long ram cylinder 25 moves on the piston 18, and I attachthis cylinder 25 at its upper end to a top cross member 26, Figs. 3 and6, that is secured to the rear side of the secondary uprights 11. Iutilize for this purpose a vertical bracket 27 that is welded to therear side of the ram cylinder 25, and that has a base portion 28 securedto the cross member 26 through bolts 29. It will be seen therefore thatthe cylinder 25 is extendible relatively to the primary uprights 10, andthat the second ram 17 is interposed between the primary and secondaryuprights 10, 11 to lift the secondary uprights. The particular rammounting does, incidentially, support the ram 17 intermediate the pairof secondary uprights 11, with the ram guided between the upper end ofthe secondary uprights 11 and the lower end of the primary uprights 10.

Before considering the ram 17 in further detail, it will be helpful torefer to the rams 30 that I utilize in my invention for lifting the loadcarriage 12 relatively to the uprights 10, 11. I arrange one ram 30 ateach side of the ram 17, but in keeping with my invention, I couldutilize a single ram if I so desired. Referring particularly to Fig. 4,each ram 30 has a cylinder 31 that is set forth as being relativelystationary and a piston 32 that is extendible relatively thereto in anupward direction. The relatively stationary ram cylinders 31 areapproximately onehalf the length of ram cylinder 25, and I attach thesecylinders 31 to the relatively movable cylinder 25 of the ram 17,utilizing for this purpose a horizontal plate or beam 33 having openingsin which the cylinders are placed and welded. Of course, since ramcylinder 25 is attached to secondary uprights 11, the plate 33 in effectsecures the ram cylinders 31 to these uprights 11. a

I prefer to make each ram cylinder 25 and 31 of th same diameter. All ofthe pistons 18 and 32 are then of the same diameter relatively to oneanother, but it is important to observe that the piston diameter issomewhat smaller than the cylinder bores. A bushing 34 holds each piston18, 32 centered at one end of its cylinder, and to guide the other endof each piston in centered relation, I mount a sectional bearing 35 in agroove near the said end of the piston. As best seen in Fig. 5, studs 36hold the sections of each bearing 35 with their ends in spaced relation,whereby fluid can flow past bearing 35 between the end and side surfacesof the piston. I equip the outer end of each ram cylinder 25, 31 with aconventional cap 37 that holds a packing 38 about the piston.

I shall now call attention to the fact that I form the piston 18 of thesecond ram 17 with an axial passage 39, Fig. 4, that extends through theupper end of piston 18. Near the bottom of piston 18 is a port 40through which a hydraulic supply line 41, Fig. 3, is in communicationwith axial passage 39, whereby fluid pressure can be applied inside theupper end of ram cylinder 25. The fluid pressure thus applied actsupwardly and, under certain conditions to be described, extends thecylinder 25 of ram 17 relatively to piston 18. In addition, the fluidpressure in the upper end of cylinder 25 acts downwardly past thesectional bearing 35 in this cylinder and along the inside 1 of thecylinder.

It will be remembered that cylinders 31 of rams 30 are rigidly attachedto ram cylinder 25, and I am able therefore to utilize rigid passagemeans for applying the fluid pressure from cylinder 25 to cylinders 31for operating rams 30. For the particular purpose, I form ports 42,Figs. 3 and 4, that extend between the interior of the ram cylinder 25and the interior of ram cylinders 31 through the intermediate parts ofthe mounting plate 33. I have already described the manner in whichfluid pressure can pass along the sides of the ram pistons 32 and pastthe sectional bearings 35 on these pistons. It will be seen thereforethat the fluid pressure that is applied through the ports 42 iseffective against the ends of pistons 32 for extending the pistonsrelatively to cylinders 31.

. in a lowered position.

Each ram piston 32 acts upon the load carriage 12 through a chain 43,Figs. 2 and 3, that is reeved over a roller 44 on the top of the piston.The particular mounting of the rollers 44 is not important, but forpurposes of description, I show a pin 46 supporting each roller 44 in aslot in the end of the piston. Each chain 43 is anchored at one endthrough a bolt 47 on the ram securing plate 33, and is attached at itsopposed end to a bracket 48 on load carriage12. ,Since the securingplate or beam 33 is attached to the secondary uprights 11 through ramcylinder 25, the chains 43 enable rams 30 to act between the secondaryuprights 11 and carriage 12. Those persons skilled in the art willunderstand that the particular chain arrangement reduces the mechanicaladvantage of each ram by one-half, since the carriage will move atdouble the speed of the ram extension. Therefore, by utilizing two rams30, with their pistons 32 of the same diameter as piston 18, I enablethe rams 30 together to exert a lifting force equal to that of the ram17. However, the rams 30 act to lift the carriage 12 'before ram 17 mayact to lift the carriage, because ram 17 must lift the secondaryuprights 11 and rams 30 in addition to the carriage.

The flow of the hydraulic fluid during the sequential movements of rams17 and 30 will be better understood if we now consider Figs. 8 and 9 ofthe drawings. Fig. 8

represents schematically the position of the rams when .both thecarriage 12 and the secondary uprights 11 are When fluid pressure isapplied through port 40 to the ram 17, this pressure flows upwardly inthe direction of the arrows against the upper end of ram cylinder 25,and downwardly outside piston 18 and through ports 42. From ports 42,the pressure flows downwardly in rams 30 and then acts upwardly againstthe ends of the pistons 32 in these rams. Since the load on pistons 32is less than on piston 18, as set forth above, the fluid pressureextends pistons 32 of rams 30, thereby lifting the load carriage 12relatively to the secondary uprights 11. When carriage 12 reaches theupper ends of the uprights 11, the outer guide rollers 16 on thecarriage move against stops 49 that I show on the secondary uprights 11in Figs. 2 and 6, thus holding the carriage 12 against further upwardmovement relatively to uprights 1L Pistons 32 are now in the positionrepresented in Fig. 9, and cylinders 31 have remained relativelystationary, being integral with cylinders 25 of ram 17. Once pistons 32have moved to the limit of their travel, shown in Fig. 9, the fluidpressure is thereafter efiective through movable cylinder 25 of ram '17to lift the secondary uprights 11 together with rams 30 and carriage 12relatively to the primary uprights 10, since both cylinders 31 of therams 30 are fixed to cylinder 25 of ram 17.

Of course,it isconceivable that rams of different diameters may beutilized toproduce the sequential movements I have described. I doprefer to utilize rams of equal diameter, since the rams are thenparticularly eflfective to lift the load carriage 12 at the same speedthroughout its entire vertical movement. This will be apparent when itis considered that the hydraulic fluid when extending the two rams 30 isdivided between these rams, but when moving ram 17 extends this ramalone. If the fluid is applied at a constant rate, with all of the rams17, 30 of the same diameter, the fluid will first extend rams 30 at aparticular speed, and will then extend ram 17 at exactly double thatspeed. Since rams 30 act through the load chains 43 that double theeffective speed of these rams, and ram 17 acts directly, it will be seenthat the load carriage 12 actually moves at the same speed whetherlifted relatively to the secondary uprights 11 through the extension oframs 30, orlifted with these uprights 11 through the extension of ram17.

The sequence in which the rams 17 and 30 act to lift the load carriage12 and secondary uprights 11 is actually the same that I describe in myearlier patent, No. 2,554,930. The extremely novel construction that Inow contribute does, however, enableme to obtain this sequentialmovement without the utilization of flexible hydraulic lines between therams. In fact, by utilizing the ports 42 in my ram securing plate 33, Iam able to eliminate all pip ng between the rams. I apply fluid pressureto the entlre ram construction through the single port 40 at the bottomof the ram 17, so that I need merely a single hydraulic line for thelifting mechanism. While accomphshing these things, I do not require acomplicated telescopic ram construction, and I am able to utilizeexceedingly simple ram structure, with a separate piston and cylinderfor each ram. In addition, by securing the ram cylinders to one another,I am able to guide all of the rams in proper aligned relation to theuprights through the attachment of the second ram between the lower endof the primary uprights and the upper end of the secondary uprights. Ibelieve, therefore, that the very considerable advantages of my novellifting mechanism will be understood, and that those skilled in the artwill appreciate fully the value of my invention.

I now claim:

1. In a truck of the class described, primary uprights, secondaryuprights mounted for vertical movement relatively to said primaryuprights, a load carriage mounted for vertical movement relatively tosaid secondary uprights, a hydraulic ram unit comprising a pair of smallrams and a large ram to which said small rams are juxtaposed with asmall ram at each side of the large ram, said large ram including anextensible element and a relatively stationary element, means securingthe lower end of the relatively stationary element of the large ramrelatively to said primary uprights and against vertical movementrelatively to said primary uprights, means securing the upper end of therelatively extensible element of said large ram to the secondaryuprights whereby said large ram is held at all times between saidsecondary and primary uprights and when actuated will lift the secondaryuprights relatively to the primary uprights, each small ram including anextensible element and a relatively stationary element, structural meanssecuring the relatively stationary element of each small ram in integralrelation to the relatively extensible element of said large ram, saidmeans rigidly fixing the relatively stationary elements of the smallrams and the relatively extensible element of the large ram to oneanother intermediate the ends thereof so that the three rams are held inaligned relationship to one another through said structural means and inoperating position between the primary and secondary uprights onlythrough the means that hold the elements of the large ram between thesecondary uprights and primary uprights, the construction andarrangement of the three-ram unit being such as to permit its assemblyto and removal from the truck as a unit through the positioning of thelarge ram relatively to the primary and secondary uprights, and flexiblemeans connected to said load carriage and actuated by the extensibleelements of said small rams whereby the small rams move said loadcarriage relatively to the secondary uprights.

2. In a truck of the class described, primary uprights, secondaryuprights mounted for vertical movement relatively to said primaryuprights, a load carriage mounted for vertical movement relatively tosaid secondary uprights, a hydraulic ram unit comprising a pair of smallrams and a large ram to which said small rams are juxtaposed with asmall ram at each side of the large ram, said large ram including anextensible element and a relatively stationary element, means securingthe lower end of the relatively stationary element of the large ramrelatively to said primary uprights and against vertical movementrelatively to said primary upl g 13163115 securing the upper end of therelatively extensible element of said large ram to the secondaryuprights whereby said large ram is held at all times between saidsecondary and primary uprights and when actuated will lift the secondaryuprights relatively to the primary uprights, each small ram including anextensible element and a relatively stationary element, a structuralmetal beam welded between the relatively stationary element of eachsmall ram and the relatively extensible element of said large ramintermediate the ends thereof, said beam rigidly fixing the relativelystationary elements of the small rams and the relatively extensibleelement of the large ram to one another so that the three rams are heldin aligned relationship to one another through said beam and inoperating position between the primary and secondary uprights onlythrough the means that hold the elements of the large ram between thesecondary uprights and primary uprights, the construction andarrangement of the three-ram unit being such as to permit its assemblyto and removal from the truck as a unit through the positioning of thelarge ram relatively to the primary and secondary uprights, and flexiblemeans connected to said load carriage and actuated by the extensibleelements of said small rams whereby the small rams move said loadcarriage relatively to the secondary uprights.

3. In a truck of the class described, primary uprights, secondaryuprights mounted for vertical movement relatively to said primaryuprights, a load carriage mounted for vertical movement relatively tosaid secondary uprights, a hydraulic ram unit comprising a pair of smallrams and a large ram to which said small rams are juxtaposed with asmall ram at each side of the large ram, said large ram including anextensible element and a relatively stationary element, means securingthe lower end of the relatively stationary element of the large ramrelatively to said primary uprights and against vertical movementrelatively to said primary uprights, means securing the upper end of therelatively extensible element of said large ram to the secondaryuprights whereby said large ram is held at all times between saidsecondary and primary uprights and when actuated will lift the secondaryuprights relatively to the primary uprights, each small ram including anextensible element and a relatively stationary element, structural metalmeans securing the relatively stationary element of each small ram inintegral relation to the relatively extensible element of said large ramintermediate the ends thereof, ports formed in said structural metalmeans for flow of hydraulic fluid between the large ram and the smallrams, said structural metal means rigidly fixing the relativelystationary elements of the small rams and the relatively extensibleelement of the large ram to one another so that the three rams are heldin aligned relationship to one another through said structural means andin operating position between the primary and secondary uprights onlythrough the means that hold the elements of the large ram between thesecondary uprights and primary uprights, the construction andarrangement of the three-ram unit being such as to permit its assemblyto and removal from the truck as a unit through the positioning of thelarge ram relatively to the primary and secondary uprights, and flexiblemeans connected to said load carriage and actuated by the extensibleelements of said small rams whereby the small rams move said loadcarriage relatively to the secondary uprights.

References Cited in the file of this patent UNITED STATES PATENTS2,678,746 Gibson May 18, 1954

